Subaqueous structure and method



D. E. MORAN. SUBAQUEOUS STRUCTURE AND METHOD.

APPLICATION FILED MAR. 22, 1916.

8 SHEETS-$HEET I.

Patented Oct. 25, 1921.

D. E.VYMORAN. SUBAQUEOUS STRUCTURE AND METHOD.

APPLICATION FILED MAR. 22, l9i6.

Patented Oct. 25, 1921.

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SUBAQUEOUS STRUCTURE AND METHOD.

APPLICATION FlLEDjMAB. 22, I9l6.

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Patented Oct. 25, 1921.

8 SHEETS-SHEET 4.

V ATTORNEY 0. E. MORAN. SUBAQUEOUS STRUCTURE AND METHOD,

APPLICATION FILED MAR- 22, I9l6.

Patented Oct. 25, 1921 B SHEETSSHEET 5.

ATTORNEY D. E. MORAN. SUBAQUEOUS smucruns AND METHOD.

APPLICATION FILED MAR. 22, I916.

Patanted Oct. 25, 1921.

SSHEETS-SHEET a.

D. E. MORAN. SUBAQUEOUS STRUCTURE AND METHOD.

APPLICATION FILED MAR. 22, 1916.

Patented Oct. 25, 1921.

8 SHEETS-SHEET 7.

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SUBAQUEOUS STRUCTURE AND METHOD. I APPLICATION FILED MAR. 22, I916. v 1 394 571. Patented Oct. 25, 1921.

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DANIEL'E. MORAN, OF MENDHAM, NEIIV JERSEY.

SUIBAQUEOUS STRUCTURE AND METHOD.

Specification of Letters Patent.

Patented Oct. 25, 1921.

Application filed March 22, 1916. Serial No. 85,801.

To all whom it may concern:

Be it known that I, DANIEL E. MORAN, a citizen of the United States, residing in Mendham, New Jersey, have invented certain new and useful Improvements in Subaqueous Structures and Methods, of which the following is a specification.

The present invention relates to the building particularly of dry docks, tunnels, pump pits, locks and similar submerged chambers, and relates generally to the building of a great variety of subaqueous structures and parts thereof such for example as the flooring and side walls or roof of a tunnel or the floor and side walls of a dry dock. The invention aims to avoid or materially reduce the difliculties heretofore encountered in the building of such structures by reason of the water pressure encountered. I propose to build first above ground (that is above the bottom or othersupport onwhich they are to rest) certain strain-supporting portions or elements of the structure and then to sink these and afterward build in place theremaining portions of the structure; all as described in detail hereinafter and pointed out in the claims at the end hereof.

The accompanying drawings illustrate structures and methods embodying the invention.

Figure 1 is a plan and Fig. 2 a transverse section of a concrete dry dock;

Fig. 3 is a section on the line 3-3 of Fig. 1 showing the work in successive stages;

Fig. 4: is a section on the line 44 of Fig. 1 showing one of the side walls in course of construction, using the cotlerdam method;

Figs. 5 and 6 are respectively a vertical section and plan of a modified form of construction; v

Figs. 7 and 8 are respectively a vertical and a horizontal section on the correspondingly numbered lines, illustrating another modification v Figs. 9, 10, 11 and 12 are vertical sections of still other modifications;

Fig. 13 is a diagram in vertical section showing a method of forming and placing the girders from the stationary platform above the site; a V

Fig. 14: is a similar view showing the forming of a girder in a floating box;

Fig. 15 is a similar view showing'the forming and sinking of a girder by means of flotation chambers;

Figs. 16 and 17 are similar views illustrating special means for forming and lowering the girders;

Fig. 18 is a partial plan of a dock floor, with one of the side walls in horizontal section on the line 18-18 of Fig. 19;

Fig. 19 is an elevation on the line 19-19 of Fig. 18, omitting the mass concrete between the premolded elements of floor and side wall;

Fig. 20 is a top plan of a portion of the side wall shown;

Fig. 21 is a section on the line 2121 of Figs. 18 and 19;

. Fig. 21* is an elevation of a floor or base carrying a pier for a bridge or the like;

Fig. 22 is a cross-section of a tunnel on the line 2222, Figs. 23 and 26;

Figs. 23, 24c, 25 and 26 are sections of the same on the correspondingly numbered lines.

In the construction of dry docks it is necessary to provide sufficient strength in the floor between the side walls to resist the upwardwater pressure when the dock is pumped out. It has been proposed to incorporate in concrete floors steel girders or similar reinforcements to transmit the strains to the side walls so as to give a relatively thin floor sufficient strength. But to construct floors in this way requires the pumping out of the excavation before the flooring can be built. This is frequently impossible because of the volume of water flowing in and the rising of the bottom of the excavation. Methods of depositing concrete through water, that is, before first pumping out the excavation, have been employed, but with such a method the concrete is liable to be damaged by the action of the water before it sets, and it is difficult and often impracticable to reinforce such concrete with steel. Pneumatic caissons or diving bells have been utilized to facilitate the placing of the concrete, but these are expensive and dangerous and generally cannot be made large enough to construct a section of concrete entirely across the width of the dock at one time.

To avoid these and similar difiiculties which have been encountered in the methods above referred to and in other old methods I proceed as follows:

First an excavation is made to the required depth, preferably by dredging and without any attempt to modify the natural water level. If the bottom is not suitable for supporting the dry-dock, and the ships therein, piling may be driven or other known means used to improve its supporting power. The sides of the excavation may be held up by sheet piling with crsos-braces extending across the excavation, or the side walls may be sloped sufficiently to hold their shape if the material is such as to permit this method.

Girders of concrete, preferably reinforced with steel in any usual or suitable way, of suiiicient length to extend clear across the floor, are constructed at some convenient point above the ground, these girders being of uniform depth from end to end or being arched on their lower chord and being shaped on their top chord to conform with the top of the floor; the excavation having been made to conform to the shape of the bottom chord of the girders. The girders may be built immediately above the sites on which they are to rest or may be built elsewhere and transferred to'such point. They are then lowered through the water until'they rest on the bottom of the excavation or on piles or other supporting means which may have been provided. The forms in which the girders are cast may be left on them so as to reinforce them during sinking, being afterward automatically detached or I removed by divers or they may be removed before the lowering of the girders. Where the form is lowered clear to the bottom with a girder the bottom piece of the form would be difficult or impossible to remove and it may be left in position so as to be incorporated in the finished structure and to contribute some strength to the floor.

Irregularity in the character of the foundation may prevent the girder from finding a uniform bearin when it is first lowered. but subsequent operations will secure a sufiicient foundation. Any irregularity in the upper surface of the foundation bed will throw the girder out of level to a corresponding extent. But in any case the extent of such departure from a true level will not be very great and the lack of perfect level will not be a matter of importance since the girder is to be embedded in a mass of concrete which can be made to fill any void or depression in the dredged bottom below the girders and which can. be properly leveled on its top surface. .These considerations give to the present girder method a great advantage over methods previously proposed for sinking large concrete units comprising a considerable portion of the length of the dock extending clear across the floor. lVith the latter structures an irregularity in the supporting power or in the level of the foundation introduces strains and the successive longitudinal portions of such a unit structure cannot accommodate themselves to a' bed which for a distance of say two or three feet longitudinally of the dock tips to the right and for the next two or three feet tips to the left; whereas the separate girders of my construction will find a good bearing 'latter act as abutments to take the upward pressure. A number of such girders are built and sunk in succession with short intervals between them. For a rectangular dock they may all be duplicates. lVhere the width of the dock varies, the length of the girders will vary accordingly, and also the depths of the different girders may be made to meet the strains arising. In fact the girders may be modified in size and shape in a great variety of ways to meet the requirements. For example, special designs will generally be used at the entrance gate of the dock and at sump wells, drainage chambers, etc. lVherever I have used a girder I may substitute an arch rib or a combination of an arch rib and a girder without departing from my invention.

Having constructed and placed a sufficient number of the girders, the floor is structurally completed by depositing concrete herein designated as mass concrete through V the water into the spacesbetween the girders and preferably underneath and for a slight depth above the girders Any usual or suitable method of depositing this concrete may be used. For example, trip-bottom buckets or tremie pipes may beused. Preferably the spaces between the girders extend clear through from. top to bottom and themass concrete which is formed in place will pass through such spaces so asto rest on the bottom of lJl'lBBXCELVZItlOIl and make contact with portions of the bottom and completely with wall may be built within a double walled cofl'erdam. The cofferdam may be built "for the entire length of a side wall, but generally it will be built in successive sections of convenient length, with suitable bulkheads at the ends. Preferably the concrete floor is made to' extend entirely under the side wall so that the bottom of the cofferdam will be held thereby and the only pumping necessary in the cofferdam will be that which is required to take care of water flowing through the coiferdam walls. Or, instead of the cofi'erdam method I may build the side walls by a method the same in general principle as my improved method described for the floor. That is I may build above ground certain strain-supporting elements of the wall, sink these preformed elements into place and afterward build in place the remaining portions of the side walls by depositin mass concrete through the water in the desired relation with said elements.

Referring now to the dock illustrated, the bottom or floor isindicated as a whole at A and the side walls at B. A rectangular dock is supposed, having a gateway Cat one end. The water level is indicated by the conventional symbol WV. L. The floor consists of girders D (Fig. 3) resting on the foundation bed or supporting material E. The girders D for a large dock may be for example, ten feet high and six feet in width at the chords and a thick I-shape in cross section, the chords of the adjacent girders being spaced apart twelve to eighteen inches. The girders are reinforced bylongitudinal rods F and Gr in the top and bottom chords respectively and by a latticed girder H of steel embedded in the central portion. The ends of the reinforcing rods F and G or of some of such rods in each girder are bent upward for any suitable height so as to form a strong tie with the side walls 13 as indicated in Fig. 4;. Also the top of the girder may be transversely recessed as at J to form a ood socket for the lower ends of the posts of the cofferdam which is used for building the side wall. Andrecesses and projections as to L and L may be made to fit into the bottom of the concrete of the side wall which is formed by casting directly on the floor. Referring back to Fig. 3 it will be understood that there may be a comparatively slight divergence of the several girders D from the perfect uniformity in level and in line with which they are shown, but each will come'to a good and independent bearing on the foundation material E and will be so nearly horizontal as to serve with substantial perfection its function of transmitting the upward strains on the floor to the abutments under the side walls. When the girders D are placed throughout the length of the dock, or for a sufiicient length to permit a progressive following up by the next step, fresh concrete is deposited in the spaces between the girders as indicated at M and substantially even with the top thereof, or alternately up to the top and slightly below the top in successive spaces as indicated for those in the left hand half of Fig. 3. The top concrete layer N of the floor is laid afterward, longitudinal reinforcing rods 0 and P being laid at suitable intervals in the height of this mass of concrete to assist in binding the successive girders together in the direction of the length of the dock. To facilitate layin the top layer N of concrete and the rods 6 and P it is preferred to build a bulkhead N across the completed floor structure and pump out the water within the bulkhead as shown, and this can be best done after building up a corresponding length of the side walls. As one suitable means for depositing the mass concrete (as distinguished from the preformed concrete elements) there is shown in Fig. 3 a pipe or tremie Q extending above water level with its lower end placed, usually by a diver, at the point where the concrete is to be deposited. A number of such pipes would generally be used. They are filled with concrete continuously and the latter pours down into the desired spaces without contact with the surrounding water until it reaches its site. The mass concrete will extend down into the bottom E to a greater or less extent depending on the character of the bottom and will close the lower ends of the spaces between the girders, so that the concrete subsequently flowing into these spaces will not be mixed with any of the earth and will easily and perfectly fill the spaces.

The top layer N of the floor may be completed to the ends of the girders before the side walls are built. Or the side walls may be built on the girders, as shown in Fig. l, and then the mass concrete extended under only a portion of the thickness of the ide walls. The side walls are built as shown in Fig. 4 by sinking posts K with facing boards R and braces S at intervals in the height and length. The coiferdam is closed at its ends and excavated and pumped out. The concrete B of the side walls is then laid, its outer vertical face being formed against the outer side of the cofferdam and its inner face being shaped by the usual forms, the braces S being removed as the concrete is extended upward.

In order to accurately position the girders D they may be formed with spacing projections T (Figs. 5 and 6) at suitable intervals in their length. In laying the girder each will be'brought with its spacing projections T butting against those of the previous girder.

Figs. 7 and 8 represent a construction which may be used with advantage when the underlying material E is soft mud. Piles U are driven at intervals depending on the character of the underlying material so as to give a sufficient bearing for the weight to be carried. Longitudinal cap V are laid on the tops of all or some of the piles. The girders D are then lowered onto these caps. Be sides having spacing wings T the lower edges of the girders are provided with extended flanges WV at intervals in their length to secure a goodbearing on the caps V. 7 Between the flanges W the lower edges of the girders are tapered downward thus providing flaring mouths at the lower ends of the spaces between the girders, so that the mass concrete deposited in such spaces will flow readily and spread under the girders and over the soft underlying material and about the head of the piles and the caps V; thus bringing the entire floor to a bearing upon the piles, and also to a bearing on the underlying material for whatever this may be worth. The same tapered shape may be given to the girders, as in Fig. 5, which rest directly on the earth, allowing a free flow of the mass concrete into any voids beneath the girders.

In some cases the underlying material may be so soft that it will permit too great a penetration of the separate comparatively narrow girders, though adapted to provide a good foundation for the finished integral floor bearing widely upon the underlying material. In such a case piles may be used as illustrated in Figs. 7 and 8, but reduced to a sufficient number merely to hold the girders which are laid on the caps on the piles. The mass concrete being then filled in will bring the completed floor to a broad bearing on the underlying material so that this may be considered the principal support, the piles, however, being left in place for the supplementary support which they provide.

Insteadof, or in addition to, the longitu-- dinal reinforcing rods laid in the top layer of the floor N as indicated in Fig. 3, reinforcement in the same direction may be provided directly between the girders. Figs. 9, 10 and 11 show reinforcement of this sort.

In Fig. 9 the girders D are provided with bars X cast therein at suitable intervals in the length of the girder and having extended ends, which are united by splice bars Y set in place by divers before the laying of the mass concrete.

In Fig. 10 the girders are provided with similar bars Z extending out of the sides of the girder at different levels and to such an extent that they will overlap when the girde s are in place. With this construction the girders cannot be lowered by a simple verti cal movement, but each girder must be lowered at ome distance from the next and then shoved sidewise into position.

In Fig. 11 the girders D are molded with transverse openings a through their webs. After they are sunk in place rods Z) are passed through said openings by divers, each rod being long enough to span sev eral girders. After the girders are laid good cemented joints and the interconnecting bars or rods set in place, the mass concrete is filled-into the spaces and will embed the exposed portions of the reinforcements and tie them firmly together and to the girders and intermediate concrete so as to constitute continuous reinforcements extending lengthwise of the dock. In this figure the base flanges are made wider than the top flanges and are laid in contact with each other so as to form a closed bottom for the. space between girders. This feature is specially useful in building roofs of submarine structures, as tunnels. Perfect tightness could be secured by packing the joint between these lower flanges, as indicated at B in Fig. 18 for example. The longitudinal reinforcement described is applicable to floors or to roofs or vertical walls or partitions.

For pumping. out or filling a dock it is advantageous to carry the water from or to a number of points distributed over its area and it 1s most convenient to utilize for thispurpose conduits extending through the floor. The present invention lends itself readily to the construction of such conduits in the manner shown for example in Fig. 12. Here each of the girders D is formed with transversely extending pipes c at in tervals in its length and of suflicient length to abut against the corresponding pipe of the next girder and so form a continuous conduit lengthwise of the dock When the mass concrete M is filled into the spaces between the girders it closes this conduitso that it can be afterward pumped dry and cleared of obstructionsand provided with at the meeting ends of the sections 0 by a man going into the conduit.

An important feature of the invention is in the method of building and placing the girders, and several variants are shown..

According to Fig. 13 the work is done from a platform located vertically over the site of the dock floor and elevated above the water level. Piles d are driven in rows be-' of the girders tween the intended positions and are provided with longitudinal .capse and cross-beams f. The figure shows the progress of the work at difl'erent stages. In

the panel at the extreme'right a half fin ished girder is shown, next a completed girder with the side forms removed, next a girder being lowered into place; 'Proceeding again to the left there is a showing of the mass concrete partially deposited and finally a showing of the completion of such deposit. Ea-ch form comprises a bottom plate 9 carrying side forms it and supported by rods 7' which are threaded through nuts carried on the cross-beams f. The concrete is poured into the forms and there are embedded in it vertical rods Z extending above the top of the girder and with an eye for attachment of the lowering means; these suspending rods being located at intervals in the length of the girder sufficient to support the latter properly throughout its length.

Then the concrete has not set sufficiently hard the side forms it are removed leaving the girder suspended by the rods j. Derricks, cranes or framework m are then lo cated above the girder carrying blocks and tackles 7% which are hooked on to the eyerods Z, and the nuts are turned to gradually lower the girder into the water, at which time the tackle is drawn taut and takes the weightof-the girder off the suspension rods. The latter are then lowered away slightly, the bottom plate 9 removed and the suspension rods also removed, leaving the naked girder supported by the tackle and guided between the piles d. By first lowering the girder into the water before taking up its weight on the tackle the weight is reduced about half,'the buoyancy being about sixtytwo and a half pounds per cubic foot and the weight of concrete in air about one hundred and twenty-five pounds. This utilization of the buoyancy of the water in handling the girders is of great importance permitting the handling of very heavy girders with engines of comparatively moderate power. 1

When mass concrete M has been introduced between two girders to a level somewhat below the tops of the girders posts 0 are erected on the previously laid girders with their upper ends bearing under the caps e to give support to the latter. The piles (Z are then cut off at the level of the finished portion of the concrete M and the space is entirely filled with such concrete, as shown in the extreme left bay of Fig. 13. The cutting off of the piles in this way is to prevent water from leaking through the finished floor, as it would around the pile if the latter extended clear to the top of the floor.

The buoyancy of the water may be utilized not only in the lowering of the finished girder, but also in the actual building of the girder. This may be done for example in the ways shown in Figs. 14 and 15. Referring first to Fig. 14: a floating box is provided, having a bottom p and sides 9. The

bottomof the box forms the bottom mold board of the girder. The side forms it are set up on the bottom and the concrete poured in to form the girder D with an embedded I-bolt Z as before. The girder may be thus formed at a distance and floated in the box to a point above its site, or the box may be placed above the site before the girder is molded therein. The girder in the box being properly located is caught by the tackles as before and its weight taken up thereby. The forms and box are then removed and the girder lowered'as before. For convenience in removing the box its bottom and sides are made separate and are held together by bolts 1" at intervals in its length, the upperend of the box being stayed by ties s and struts t at suitable points, which ties and struts are also readily removable.

In Fig. 15 there is a similar box with bot tom p and sides 9 in which the girder D is molded as before. The box, however, is supportedby flotation chambers u on the top of which rest beams o carrying crossbeams to which support bolts r which hold the box together. There is also supported from one of the cross-beams w hooks a; which engage the I-bolts Z that are embedded in the girder. The flotation chambers are provided with pipes e for air and z for water, so that the air capacity of the chambers can be varied as desired by pumping water into and out of them. This flotation apparatus is located immediately above the site of the girder, either before or after the molding of the latter. When the girder is hardened the forms are removed. The bolts 1 are then released and the bottom and sides of the box removed leaving the naked concrete in the water supported by the flotation chambers and the longitudinal and cross-beams thereon. By gradually increasing the water in the chambers u the girder is lowered to its position on the bed of the excavation, after which the hooks m are withdrawn and the flotation chambers raised for the next operation.

To increase the stiffness of the girder while it is being handled the form may be left in place, removing only the sides thereof after it is sunk. And the form may be designed so as to constitute in itself a girder of considerable stiffness or may be connected with a special girder for the purpose of avoiding unequal strains at different points in the length of the girder while it is being handled. Fig. 16 shows a form comprising steel sides 2 having upward extensions 3 which give great depth to the structure and corresponding stiffness, the side forms having inward flanges f constituting the bottom of the mold and bolted together as shown. A girder D built in such a mold may be supported by the tackles overhead by I-bolts Z embedded in the concrete. When it is nearly in place th bottom bolts 5 of the form may be withdrawn and the form removed and the girder lowered to its resting place.

Or a form such as is shown in Fig. 17 may be employed comprising a box with a bottom 39 and sides Q as previously described, additional girders 6 being attached to the sides of the box to contribute additional stiffness. The tackle n in this case is attached to the girders 6 and the whole structure will be lowered on the bottom before the girder 6 and the side plates 9 and side forms it are removed; the bottom board 39 being left in place.

Or the bottom may be saved if the girder 6 be arranged to carry hooks 7 engaging I- bolts Z of the girder. The removal of the bottom and sides of the box shortly before the girder reaches its resting place will leave the girder suspended from the hooks 7 and it may be subsequently lowered ontothe bottom and the hooks 7 and girder 6 raised by the tackle.

The method is applicable not only to the building of the floor of a dry dock as above explained, but also to the buidling of various elements of other structures. In Figs. 18 to 21 I have illustrated the method applied to not only the floor, but also to side walls of a dry dock. The floor is made up of premolded concrete girders D as in the previously described constructions, with mass concrete M filling the spaces between them, and with their flanges reinforced by embedded rods F and G. The sidewall B is built up of premolcled elements B of concrete in the form ofcolumns approximately I-shaped in horizontal section. These columns are molded above ground and lowered into'place in any of the ways described for molding and lowereing the floor girders. After a suflicient number of floor girders D have been placed on the bottom of the excavation and united into a structurally complete concrete floor by depositing mass concrete in the spaces between adjacent girders and between the girders and the bottom of the excavation I place concrete wall elements each element (as B, Figs. 18, 19, 20 and 21) consisting of a concrete casting suitably reinforced with reinforcing or structural steel. Each element B is of the required height to extend from the top of the concrete floor to a point above water level. One face is substantially vertical corresponding to the form adopted for the outer face of the side wall, the opposite face is inclined and corresponds to the form adopted for the inner face of the side wall and may be stepped or may form part of a timber slide or part of an entrance gate or caisson seat corresponding to the general design of the dock at the point at which the element is used. Each element when placed in proper position to form part of the wall is in juxtaposition with a previously placed elementand forms one of a series of such elements. The bases of the elements rest on the upper surface of the previously constructed concrete floor and preferably each element has projections and recesses molded in its base corresponding with similar recesses and projections on the upper surface of the ends of the concrete floor girders as at L, Fig. 19 so as to securely engage with the floor and to provide against any sliding or displacement of the elements or of the completed side wall.

The exterior faces of adjoining elements form a nearly continuous exterior face for the wall, and the interior faces of adjoining elements form a nearly continuous interior face for the wall.

The faces of each element at right angles to the length of the wall, which faces adjoin adjacent elements are recessed so as to form a considerable space between adjoining elements as at B Figs. 18 and 20. A horizontal cross section of an element at any elevation is therefore in general an H-shape as indicated in Figs. 18 and 20.

Each element may be considered as a vertical girder or beam having a flange forming part of the exterior face of the wall and a flange forming part of the interior face of a the wall, the two flanges being connected by a web. The concrete forming each element may be reinforced so as to enable it to securely resist the external pressure dueto the water and soil pressure which will be exerted on its external face. Such reinforcing may be placed as shown at F and G in Fig. 18 or as otherwise required.

Having placed a number of such elements I proceed to complete the wall structure by depositing concrete B Fig. 21, in the spaces B provided between adjacent elements, completely filling the spaces between elements from the previously completed concrete 'floor up to a point above water level.

In order to unite the elements and the filling or mass concrete B I provide or form keys or projections B on the inner faces of the concrete elements or I may provide metallic ties by embedding reinforcing steel in the concrete of the element allowing parts thereof to project into the spaces B which parts will be embedded in the mass concrete B 7 In order to prevent any loss of concrete mortar between the abutting edges of the flanges of adjoining elements, I provide suitable packing as shown at 13, Figs. 18, 20 and 21, or other means familiar to persons skilled in the art, to prevent leakage. In

order to insure that the side walls will not overturn as a result of the external pressure due to soil and water exterior to'the between the vertical elements of the side walls. Such reinforcement is shown in Figs. 19 and 21 at F and G. 'When these spacesare filled with mass concrete B the reinforcing rods will be embedded therein and will act to prevent the side wall from overturning. 1

In order to unite the various elements, and V the mass concrete into a wall possessing great longitudinal strength I provide openings B Fig. 19, in the web of each vertical element. Thesefopenings will insure cohesion between the mass concrete placed in adjoining spaces B and also permit of the placing of reinforcing steel F Fig. 21, in horizontal lines so as toincrease the longitudinal strength of the wall.

The construction of my vertical wall is the same in general principle as the construction of my floor, and it is evident that I may use vertical girders as described for the sidewalls and partition walls of tunnels or other subaqueous structures and that I may use my method of floor construction for the floors or roofs of subaqueous tunnels, or for subaqueous spread foundations for bridge piers or for other subaqueous constructions. The pier B, Fig. 21 for example, may be built on the same principle, supported on a footing or base or grillage formed of girders D like the dock floor described, and with the reinforcing rods F and Gr of the floor girders running up into the pier to tie the two structures together.

In Figs. 22 to 26 I have illustrated more or less diagrammatically the application of substantially the same method to the building of a subaqueous tunnel by way of ex ample. In this construction floor girders or beams 8 are premolded and then sunk into place and mass concrete 9 deposited to fill the spaces between the girders and complete the floor. The girders are formed with their lower flanges extended at the end as'at 10 and their upper flanges cut away at the end to form tongues 11. The side wall is formed of elements in the form of posts or vertical beams 12 premolded above ground and then lowered into place, their lower ends being reduced in width, as shown in Fig. 25, to fit between the spacing tongues 11 of the floor girders. The wall elements or sections 12 have spaces of any suitable shape and size between them which are subsequently filled with tremie concrete 13. In building the tunnel the floor beams 8 will be laid first. The side wall elements 12 may then be erected before introducing the mass concrete 9 between the floor girders, so that such concrete will engage and adhere to the under ends of the wall sections. These sections are preferably also made with grooves 14 (Fig. 25) in their lower portions, facing the spaces between the girders so as to be keyed to the mass concrete and thus unite the girders more strongly to the wall sections. Fig. 18 shows a tunnel made with a bottom or floor 15, an outside wall 16, an interior partition 17 and a roof 18. The method described for laying the floor may be repeated for the roof; the girders 19, Fig. 26, having their lower'flanges in contact to hold the mass concrete 20 between them. The method employed for theside walls may be used with suitable modification for the interior partition.

On the same principle various other subaqueous structures or parts thereof may be built without departing from the invention as defined in the following claims. The term floor is used herein to cover various equivalent horizontally disposed slabs, such as a base for a bridge pier or the like, or a roof; and the walls of most structures built according to this invention are analogous to the floors since in use the premolded posts or columnar elements thereof sustain horizontal strains, which, of course, are transverse to their length, and thus act in great part like beams or girders.

I am aware that gravity dams or breakwaters have been built up of separate blocks of concrete sunk into place on the bottom of the waterway. The present invention applies to a different class of structures, to structures which are subject to flexural stresses, like the dry dock floor which is pressed downward at the sides by the weight of its walls and upward at the center by the water pressure beneath, or like the side walls of the dry dock which are held fast at their lower ends and are subject to lateral hydraulic pressure tending to bend the top inward, or like the roof of a tunnel which is held upward at its sides and pressed downward at its'center. The gravity dams referred to are made so heavy and of such shape that the only stresses to be taken into serious consideration are the uniform pressures over the face of the dam, which tend to slide it along the bottom or to tilt it about its heel. There are also framed dams in which, as far as I am aware, the fiexuralstrain-supporting elements have been made of steel or wood and these elements have been united by the material forming the face of the dam; but I do not believe that dams of this type have been built according to the method herein described and claimed.

In the gravity dams and similar structures referred to each of the parts which is separately sunk is designed to withstand not only the strains which arise on account of its weight when it is set in place but also the strains which occur when the structure is in actual use. That is to say, each separate part of the structure will by itself withstand the strains of use, such parts being sometimes entirely without connection between them and sometimes with a connection which is designed merely to prevent the passage of water, but not to distribute the strains on one of the parts to the neighboring part. The girders of this invention when they are first laid act independently.

But after the structure is completed the 'glrders act jointly. If one girder is subissrifliciently strong and binding to transfer a part .of the strain to the girders on eithe side. Thus in the finished structure We have a capability of resistance against concentrated loads or strains very much greater than any strength possessed by the separate girders when they are first laid.

What I claim is- 1. A method of building concrete dry docks or the like which comprises molding above ground concrete floor girders adapted to extend across the Width of said dock,

"sinking said molded girders separately through the Water into them to come to independent bearings on the place and allowing underlying support, depositing mass concrete through the water in plastic condition betWeen 'saidgirders to firmly unite them above jointly so as to'make a-continuous floor structure, and building up the side walls of the dock on the ends of said girders.

2. In the building of subaqueous structures the method Which comprises molding g ound concrete fioor'girders, sinking these separately through the water into place and allowing-them to come to independent bearings on the underlying support, and de' positing concrete through the Water between said girders to firmly unit-e them and to distribute the strains among them jointly so as to make a continuous floor structure, also molding above ground certain strain-resist lng elements of a Wall, sinking these separately into place on the floor and depositing mass concrete through the Water in plastic condition in the desired relation With said elements of the wall to complete such wall.

In Witness whereof, I have hereunto signed my name.

DANIEL E. MORAN. 

